CVE-2026-85394
CVE-2026-85394
python-jose through 3.5.0 fails to properly validate asymmetric keys in HMAC initialization, accepting DER-encoded public keys that lack PEM armor or SSH prefixes. Attackers holding the service's public key can forge HS256 tokens that pass verification when algorithms are not explicitly restricted. This is an incomplete fix for CVE-2024-33663.
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-85394?
- CVE-2026-85394 is a critical-severity vulnerability, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.1/10. Published 2026-09-03.
- How severe is CVE-2026-85394?
- Critical severity. CVSS v3 base score is 9.1 out of 10.